OO-798, OO-797, OO-796: update the webdav implementation based on Tomcat, make OpenOLAt work under root context, small refactoring of the dispatchers, push raw files dispatcher to its own servlet, implements Digest authentication...

OO-466: control indexer and notifications periodically jobs only via quartz scheduler, cron expression customizable, RESt API to trigger the two jobs

OO-449: first part of the implementation: remove smack libraries, refactor controller and unify them, implements messaging across the OpenOLAT event bus, implements administration part to enable chat...

OO-271: refactor the user session management, move the the logic in its own manager, persist the time out values, make the admin GUI a bit better

OO-340: enhance the rest api to monitor OpenOLAT, add more informations for memory, configuration for probes, dependencies infos...